/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */
package javax.swing;

import java.awt.AWTKeyStroke;
import java.awt.event.KeyEvent;

A KeyStroke represents a key action on the keyboard, or equivalent input
device. KeyStrokes can correspond to only a press or release of a particular
key, just as KEY_PRESSED and KEY_RELEASED KeyEvents do; alternately, they
can correspond to typing a specific Java character, just as KEY_TYPED
KeyEvents do. In all cases, KeyStrokes can specify modifiers (alt, shift,
control, meta, altGraph, or a combination thereof) which must be present during the
action for an exact match.

KeyStrokes are used to define high-level (semantic) action events. Instead
of trapping every keystroke and throwing away the ones you are not
interested in, those keystrokes you care about automatically initiate
actions on the Components with which they are registered.

KeyStrokes are immutable, and are intended to be unique. Client code cannot
create a KeyStroke; a variant of getKeyStroke must be used
instead. These factory methods allow the KeyStroke implementation to cache
and share instances efficiently.

Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing.  As of 1.4, support for long term storage
of all JavaBeans™
has been added to the java.beans package. Please see XMLEncoder. 
Author:
Arnaud Weber, David Mendenhall
See Also:
Keymap
getKeyStroke/**
 * A KeyStroke represents a key action on the keyboard, or equivalent input
 * device. KeyStrokes can correspond to only a press or release of a particular
 * key, just as KEY_PRESSED and KEY_RELEASED KeyEvents do; alternately, they
 * can correspond to typing a specific Java character, just as KEY_TYPED
 * KeyEvents do. In all cases, KeyStrokes can specify modifiers (alt, shift,
 * control, meta, altGraph, or a combination thereof) which must be present during the
 * action for an exact match.
 * <p>
 * KeyStrokes are used to define high-level (semantic) action events. Instead
 * of trapping every keystroke and throwing away the ones you are not
 * interested in, those keystrokes you care about automatically initiate
 * actions on the Components with which they are registered.
 * <p>
 * KeyStrokes are immutable, and are intended to be unique. Client code cannot
 * create a KeyStroke; a variant of <code>getKeyStroke</code> must be used
 * instead. These factory methods allow the KeyStroke implementation to cache
 * and share instances efficiently.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans&trade;
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @see javax.swing.text.Keymap
 * @see #getKeyStroke
 *
 * @author Arnaud Weber
 * @author David Mendenhall
 */
public class KeyStroke extends AWTKeyStroke {

    
Serial Version ID.
/**
     * Serial Version ID.
     */
    private static final long serialVersionUID = -9060180771037902530L;

    private KeyStroke() {
    }
    private KeyStroke(char keyChar, int keyCode, int modifiers,
                      boolean onKeyRelease) {
        super(keyChar, keyCode, modifiers, onKeyRelease);
    }

    
Returns a shared instance of a KeyStroke
that represents a KEY_TYPED event for the
specified character.
Params:
keyChar – the character value for a keyboard key
Returns:
a KeyStroke object for that key/**
     * Returns a shared instance of a <code>KeyStroke</code>
     * that represents a <code>KEY_TYPED</code> event for the
     * specified character.
     *
     * @param keyChar the character value for a keyboard key
     * @return a KeyStroke object for that key
     */
    public static KeyStroke getKeyStroke(char keyChar) {
        synchronized (AWTKeyStroke.class) {
            registerSubclass(KeyStroke.class);
            return (KeyStroke)getAWTKeyStroke(keyChar);
        }
    }

    
Returns an instance of a KeyStroke, specifying whether the key is
considered to be activated when it is pressed or released. Unlike all
other factory methods in this class, the instances returned by this
method are not necessarily cached or shared.
Params:
keyChar – the character value for a keyboard key
onKeyRelease – true if this KeyStroke corresponds to a
       key release; false otherwise.
Returns:
a KeyStroke object for that key
Deprecated:
use getKeyStroke(char)/**
     * Returns an instance of a KeyStroke, specifying whether the key is
     * considered to be activated when it is pressed or released. Unlike all
     * other factory methods in this class, the instances returned by this
     * method are not necessarily cached or shared.
     *
     * @param keyChar the character value for a keyboard key
     * @param onKeyRelease <code>true</code> if this KeyStroke corresponds to a
     *        key release; <code>false</code> otherwise.
     * @return a KeyStroke object for that key
     * @deprecated use getKeyStroke(char)
     */
    @Deprecated
    public static KeyStroke getKeyStroke(char keyChar, boolean onKeyRelease) {
        return new KeyStroke(keyChar, KeyEvent.VK_UNDEFINED, 0, onKeyRelease);
    }

    
Returns a shared instance of a KeyStroke that represents a KEY_TYPED event for the specified Character object and a set of modifiers. Note that the first parameter is of type Character rather than char. This is to avoid inadvertent clashes with calls to getKeyStroke(int keyCode, int modifiers).
The modifiers consist of any combination of following:

java.awt.event.InputEvent.SHIFT_DOWN_MASK
java.awt.event.InputEvent.CTRL_DOWN_MASK
java.awt.event.InputEvent.META_DOWN_MASK
java.awt.event.InputEvent.ALT_DOWN_MASK
java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK

The old modifiers listed below also can be used, but they are
mapped to _DOWN_ modifiers. 

java.awt.event.InputEvent.SHIFT_MASK
java.awt.event.InputEvent.CTRL_MASK
java.awt.event.InputEvent.META_MASK
java.awt.event.InputEvent.ALT_MASK
java.awt.event.InputEvent.ALT_GRAPH_MASK

also can be used, but they are mapped to _DOWN_ modifiers.
Since these numbers are all different powers of two, any combination of
them is an integer in which each bit represents a different modifier
key. Use 0 to specify no modifiers.
Params:
keyChar – the Character object for a keyboard character
modifiers – a bitwise-ored combination of any modifiers
Throws:
IllegalArgumentException – if keyChar is null
See Also:
InputEvent
Returns:
an KeyStroke object for that key
Since:
1.3/**
     * Returns a shared instance of a {@code KeyStroke}
     * that represents a {@code KEY_TYPED} event for the
     * specified Character object and a
      * set of modifiers. Note that the first parameter is of type Character
     * rather than char. This is to avoid inadvertent clashes with calls to
     * <code>getKeyStroke(int keyCode, int modifiers)</code>.
     *
     * The modifiers consist of any combination of following:<ul>
     * <li>java.awt.event.InputEvent.SHIFT_DOWN_MASK
     * <li>java.awt.event.InputEvent.CTRL_DOWN_MASK
     * <li>java.awt.event.InputEvent.META_DOWN_MASK
     * <li>java.awt.event.InputEvent.ALT_DOWN_MASK
     * <li>java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK
     * </ul>
     * The old modifiers listed below also can be used, but they are
     * mapped to _DOWN_ modifiers. <ul>
     * <li>java.awt.event.InputEvent.SHIFT_MASK
     * <li>java.awt.event.InputEvent.CTRL_MASK
     * <li>java.awt.event.InputEvent.META_MASK
     * <li>java.awt.event.InputEvent.ALT_MASK
     * <li>java.awt.event.InputEvent.ALT_GRAPH_MASK
     * </ul>
     * also can be used, but they are mapped to _DOWN_ modifiers.
     *
     * Since these numbers are all different powers of two, any combination of
     * them is an integer in which each bit represents a different modifier
     * key. Use 0 to specify no modifiers.
     *
     * @param keyChar the Character object for a keyboard character
     * @param modifiers a bitwise-ored combination of any modifiers
     * @return an KeyStroke object for that key
     * @throws IllegalArgumentException if keyChar is null
     *
     * @see java.awt.event.InputEvent
     * @since 1.3
     */
    public static KeyStroke getKeyStroke(Character keyChar, int modifiers) {
        synchronized (AWTKeyStroke.class) {
            registerSubclass(KeyStroke.class);
            return (KeyStroke)getAWTKeyStroke(keyChar, modifiers);
        }
    }

    
Returns a shared instance of a KeyStroke, given a numeric key code and a
set of modifiers, specifying whether the key is activated when it is
pressed or released.

The "virtual key" constants defined in java.awt.event.KeyEvent can be
used to specify the key code. For example:

java.awt.event.KeyEvent.VK_ENTER
java.awt.event.KeyEvent.VK_TAB
java.awt.event.KeyEvent.VK_SPACE

Alternatively, the key code may be obtained by calling
java.awt.event.KeyEvent.getExtendedKeyCodeForChar.
The modifiers consist of any combination of:

java.awt.event.InputEvent.SHIFT_DOWN_MASK
java.awt.event.InputEvent.CTRL_DOWN_MASK
java.awt.event.InputEvent.META_DOWN_MASK
java.awt.event.InputEvent.ALT_DOWN_MASK
java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK

The old modifiers 

java.awt.event.InputEvent.SHIFT_MASK
java.awt.event.InputEvent.CTRL_MASK
java.awt.event.InputEvent.META_MASK
java.awt.event.InputEvent.ALT_MASK
java.awt.event.InputEvent.ALT_GRAPH_MASK

also can be used, but they are mapped to _DOWN_ modifiers.
Since these numbers are all different powers of two, any combination of
them is an integer in which each bit represents a different modifier
key. Use 0 to specify no modifiers.
Params:
keyCode – an int specifying the numeric code for a keyboard key
modifiers – a bitwise-ored combination of any modifiers
onKeyRelease – true if the KeyStroke should represent
       a key release; false otherwise.
See Also:
KeyEvent
InputEvent
Returns:
a KeyStroke object for that key/**
     * Returns a shared instance of a KeyStroke, given a numeric key code and a
     * set of modifiers, specifying whether the key is activated when it is
     * pressed or released.
     * <p>
     * The "virtual key" constants defined in java.awt.event.KeyEvent can be
     * used to specify the key code. For example:<ul>
     * <li>java.awt.event.KeyEvent.VK_ENTER
     * <li>java.awt.event.KeyEvent.VK_TAB
     * <li>java.awt.event.KeyEvent.VK_SPACE
     * </ul>
     * Alternatively, the key code may be obtained by calling
     * <code>java.awt.event.KeyEvent.getExtendedKeyCodeForChar</code>.
     *
     * The modifiers consist of any combination of:<ul>
     * <li>java.awt.event.InputEvent.SHIFT_DOWN_MASK
     * <li>java.awt.event.InputEvent.CTRL_DOWN_MASK
     * <li>java.awt.event.InputEvent.META_DOWN_MASK
     * <li>java.awt.event.InputEvent.ALT_DOWN_MASK
     * <li>java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK
     * </ul>
     * The old modifiers <ul>
     * <li>java.awt.event.InputEvent.SHIFT_MASK
     * <li>java.awt.event.InputEvent.CTRL_MASK
     * <li>java.awt.event.InputEvent.META_MASK
     * <li>java.awt.event.InputEvent.ALT_MASK
     * <li>java.awt.event.InputEvent.ALT_GRAPH_MASK
     * </ul>
     * also can be used, but they are mapped to _DOWN_ modifiers.
     *
     * Since these numbers are all different powers of two, any combination of
     * them is an integer in which each bit represents a different modifier
     * key. Use 0 to specify no modifiers.
     *
     * @param keyCode an int specifying the numeric code for a keyboard key
     * @param modifiers a bitwise-ored combination of any modifiers
     * @param onKeyRelease <code>true</code> if the KeyStroke should represent
     *        a key release; <code>false</code> otherwise.
     * @return a KeyStroke object for that key
     *
     * @see java.awt.event.KeyEvent
     * @see java.awt.event.InputEvent
     */
    public static KeyStroke getKeyStroke(int keyCode, int modifiers,
                                         boolean onKeyRelease) {
        synchronized (AWTKeyStroke.class) {
            registerSubclass(KeyStroke.class);
            return (KeyStroke)getAWTKeyStroke(keyCode, modifiers,
                                              onKeyRelease);
        }
    }

    
Returns a shared instance of a KeyStroke, given a numeric key code and a
set of modifiers. The returned KeyStroke will correspond to a key press.

The "virtual key" constants defined in java.awt.event.KeyEvent can be
used to specify the key code. For example:

java.awt.event.KeyEvent.VK_ENTER
java.awt.event.KeyEvent.VK_TAB
java.awt.event.KeyEvent.VK_SPACE

Alternatively, the key code may be obtained by calling
java.awt.event.KeyEvent.getExtendedKeyCodeForChar.
The modifiers consist of any combination of:

java.awt.event.InputEvent.SHIFT_DOWN_MASK
java.awt.event.InputEvent.CTRL_DOWN_MASK
java.awt.event.InputEvent.META_DOWN_MASK
java.awt.event.InputEvent.ALT_DOWN_MASK
java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK

The old modifiers 

java.awt.event.InputEvent.SHIFT_MASK
java.awt.event.InputEvent.CTRL_MASK
java.awt.event.InputEvent.META_MASK
java.awt.event.InputEvent.ALT_MASK
java.awt.event.InputEvent.ALT_GRAPH_MASK

also can be used, but they are mapped to _DOWN_ modifiers.
Since these numbers are all different powers of two, any combination of
them is an integer in which each bit represents a different modifier
key. Use 0 to specify no modifiers.
Params:
keyCode – an int specifying the numeric code for a keyboard key
modifiers – a bitwise-ored combination of any modifiers
See Also:
KeyEvent
InputEvent
Returns:
a KeyStroke object for that key/**
     * Returns a shared instance of a KeyStroke, given a numeric key code and a
     * set of modifiers. The returned KeyStroke will correspond to a key press.
     * <p>
     * The "virtual key" constants defined in java.awt.event.KeyEvent can be
     * used to specify the key code. For example:<ul>
     * <li>java.awt.event.KeyEvent.VK_ENTER
     * <li>java.awt.event.KeyEvent.VK_TAB
     * <li>java.awt.event.KeyEvent.VK_SPACE
     * </ul>
     * Alternatively, the key code may be obtained by calling
     * <code>java.awt.event.KeyEvent.getExtendedKeyCodeForChar</code>.
     *
     * The modifiers consist of any combination of:<ul>
     * <li>java.awt.event.InputEvent.SHIFT_DOWN_MASK
     * <li>java.awt.event.InputEvent.CTRL_DOWN_MASK
     * <li>java.awt.event.InputEvent.META_DOWN_MASK
     * <li>java.awt.event.InputEvent.ALT_DOWN_MASK
     * <li>java.awt.event.InputEvent.ALT_GRAPH_DOWN_MASK
     * </ul>
     * The old modifiers <ul>
     * <li>java.awt.event.InputEvent.SHIFT_MASK
     * <li>java.awt.event.InputEvent.CTRL_MASK
     * <li>java.awt.event.InputEvent.META_MASK
     * <li>java.awt.event.InputEvent.ALT_MASK
     * <li>java.awt.event.InputEvent.ALT_GRAPH_MASK
     * </ul>
     * also can be used, but they are mapped to _DOWN_ modifiers.
     *
     * Since these numbers are all different powers of two, any combination of
     * them is an integer in which each bit represents a different modifier
     * key. Use 0 to specify no modifiers.
     *
     * @param keyCode an int specifying the numeric code for a keyboard key
     * @param modifiers a bitwise-ored combination of any modifiers
     * @return a KeyStroke object for that key
     *
     * @see java.awt.event.KeyEvent
     * @see java.awt.event.InputEvent
     */
    public static KeyStroke getKeyStroke(int keyCode, int modifiers) {
        synchronized (AWTKeyStroke.class) {
            registerSubclass(KeyStroke.class);
            return (KeyStroke)getAWTKeyStroke(keyCode, modifiers);
        }
    }

    
Returns a KeyStroke which represents the stroke which generated a given
KeyEvent.

This method obtains the keyChar from a KeyTyped event, and the keyCode
from a KeyPressed or KeyReleased event. The KeyEvent modifiers are
obtained for all three types of KeyEvent.
Params:
anEvent – the KeyEvent from which to obtain the KeyStroke
Throws:
NullPointerException – if anEvent is null
Returns:
the KeyStroke that precipitated the event/**
     * Returns a KeyStroke which represents the stroke which generated a given
     * KeyEvent.
     * <p>
     * This method obtains the keyChar from a KeyTyped event, and the keyCode
     * from a KeyPressed or KeyReleased event. The KeyEvent modifiers are
     * obtained for all three types of KeyEvent.
     *
     * @param anEvent the KeyEvent from which to obtain the KeyStroke
     * @throws NullPointerException if <code>anEvent</code> is null
     * @return the KeyStroke that precipitated the event
     */
    public static KeyStroke getKeyStrokeForEvent(KeyEvent anEvent) {
        synchronized (AWTKeyStroke.class) {
            registerSubclass(KeyStroke.class);
            return (KeyStroke)getAWTKeyStrokeForEvent(anEvent);
        }
    }

    
Parses a string and returns a KeyStroke.
The string must have the following syntax:
   <modifiers>* (<typedID> | <pressedReleasedID>)
   modifiers := shift | control | ctrl | meta | alt | altGraph
   typedID := typed <typedKey>
   typedKey := string of length 1 giving Unicode character.
   pressedReleasedID := (pressed | released) key
   key := KeyEvent key code name, i.e. the name following "VK_".

If typed, pressed or released is not specified, pressed is assumed. Here
are some examples:
    "INSERT" => getKeyStroke(KeyEvent.VK_INSERT, 0);
    "control DELETE" => getKeyStroke(KeyEvent.VK_DELETE, InputEvent.CTRL_MASK);
    "alt shift X" => getKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK);
    "alt shift released X" => getKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK, true);
    "typed a" => getKeyStroke('a');

In order to maintain backward-compatibility, specifying a null String,
or a String which is formatted incorrectly, returns null.
Params:
s – a String formatted as described above
See Also:
KeyEvent
Returns:
a KeyStroke object for that String, or null if the specified
        String is null, or is formatted incorrectly/**
     * Parses a string and returns a <code>KeyStroke</code>.
     * The string must have the following syntax:
     * <pre>
     *    &lt;modifiers&gt;* (&lt;typedID&gt; | &lt;pressedReleasedID&gt;)
     *
     *    modifiers := shift | control | ctrl | meta | alt | altGraph
     *    typedID := typed &lt;typedKey&gt;
     *    typedKey := string of length 1 giving Unicode character.
     *    pressedReleasedID := (pressed | released) key
     *    key := KeyEvent key code name, i.e. the name following "VK_".
     * </pre>
     * If typed, pressed or released is not specified, pressed is assumed. Here
     * are some examples:
     * <pre>
     *     "INSERT" =&gt; getKeyStroke(KeyEvent.VK_INSERT, 0);
     *     "control DELETE" =&gt; getKeyStroke(KeyEvent.VK_DELETE, InputEvent.CTRL_MASK);
     *     "alt shift X" =&gt; getKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK);
     *     "alt shift released X" =&gt; getKeyStroke(KeyEvent.VK_X, InputEvent.ALT_MASK | InputEvent.SHIFT_MASK, true);
     *     "typed a" =&gt; getKeyStroke('a');
     * </pre>
     *
     * In order to maintain backward-compatibility, specifying a null String,
     * or a String which is formatted incorrectly, returns null.
     *
     * @param s a String formatted as described above
     * @return a KeyStroke object for that String, or null if the specified
     *         String is null, or is formatted incorrectly
     *
     * @see java.awt.event.KeyEvent
     */
    public static KeyStroke getKeyStroke(String s) {
        if (s == null || s.length() == 0) {
            return null;
        }
        synchronized (AWTKeyStroke.class) {
            registerSubclass(KeyStroke.class);
            try {
                return (KeyStroke)getAWTKeyStroke(s);
            } catch (IllegalArgumentException e) {
                return null;
            }
        }
    }
}